RESPONSE ALTERNATION AFTER TWO FORCED TURNS ON THE SAME ELEVATED ALLEYS AS A FUNCTION OF INTER-TRIAL INTERVALS IN THE WHITE RAT

Turn alternation immediately following forced turns in the same maze has generally been interpreted by the centrifugal swing concept, while the inhibition concept whether it is movement-produced stimulus inhibition or external stimulus inhibition, has been used in explaining spontaneous alternation between temporally isolated free turns in a simple T-maze. However, to the present authors, there appears no reason why the two phenomena should be differentiated. The purpose of the present study is to test whether the inhibition or the swing concept has generality in explaining the phenomenon.Rats were run five trials daily for two blocks of a two days' session under 23 hours of food deprivation. Narrow elevated alleys without walls were used in order to minimize the role of centrifugal swing. The apparatus used are shown in Fig. 1. The inhibition hypothesis predicts response alternation at the choice point after two forced turns and, in addition, spontaneous alternation between two successive free choices is expected as a function of inter-trial intervals. The same results could not be derived from the centrifugal swing concept because of the very nature of the apparatus and inter-trial response alternation could be neither explainable in terms of centrifugal swing.Both massed (0″ interval) and spaced (60″ interval) groups showed a tendency to avoid previous forced turns for the total trials as well as for the initial trials. VTE's and body weight did not correlate with the phenomenon. Inter-trial response alternation was found to be more frequent for the massed group than for the spaced group. Color and position habits were carefully eliminated by using two alternate mirror apparatus (Fig. 1). VTE's were unrelated to the opposite-turning tendency. The results in general agreed with the inhibition hypothesis in contrast to the centrifugal swing concept.